**Core Concept**
Metallic oxides are added to porcelain to alter its color, translucency, and strength. This process is known as **glazing**, where the oxides undergo a reduction-oxidation reaction to produce the desired properties.

**Why the Correct Answer is Right**
The correct answer is related to the **redox reaction** that occurs between the metallic oxides and the porcelain. When heated, the oxides undergo a reduction reaction, releasing oxygen ions that combine with the porcelain's silica and alumina to form a glassy coating. This coating enhances the porcelain's strength, durability, and aesthetic appeal. The specific oxides used determine the resulting color and properties of the porcelain.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because while metallic oxides do affect the color, they are not added solely for this purpose.
**Option B:** Incorrect because the primary function of metallic oxides is not to alter the porcelain's translucency.
**Option C:** Incorrect because while oxides can affect the porcelain's strength, this is not their primary purpose in glazing.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the type and proportion of metallic oxides used in glazing can significantly impact the porcelain's final properties. This is an important consideration in dental and medical applications, where the material's strength and durability are crucial.

**Correct Answer: C. To enhance the porcelain's strength and durability.**